Closed end sleeve-like boss and method of making



Oct. 20, 1959 o. M. KosKlNEN 25,909,28E

CLOSED END SLEEVE-'LIKE BOSS AND METHOD OF MAKING Filed May 19, 1954 2Sheets-Sheet 1 M @L @i Oct. 20, 1959 O. M. KOSKINEN CLOSED ENDSLEEVE-LIKE BOSS AND METHOD OF MAKING Filed May 19, 1954 2 Sheets-Sheet2 IN V EN TOR. 02m/z /fas 71627.

United States Patent() A'2,9"'0'9,`2"fi1 CLosED END SLEEVE-LIKE :BossMETHOD EoF MAKING olagvi M. Koskincn, handlichem, Mich., assigner toChrysler Corporation, Highland Park, Mich., a coi'poration of Delaware jl Application May r19, 1954, serial No. 430,863

z claims. l(ci. 207-6) This invention relates to 'sleeve-like bossesthat have knock-out integrally formed plugs 'that are removable 's'othat the bosses 'may receive bolts or Athe like, and to the method offorming su'ch bosses.

It is a primary object 'of this invention to provide a closed end,sleeve-like bo's's 'on which 'the 'end 'closure portion can be readilyknocked ou't and the boss internally threaded to provide as'ati'sfaetory bolt receiving formatio'n.

Itis another object of this invention to provide a sleevelike boss inwhich its 'method o'f forming work harden's the material forming' theboss and 'thus improves its texture for machining, wearability, andthelike.

It is still another object of this invention 'to provide a boss formingmethod that will provide 'relatively deep, symmetrical, sturdy,Work-hardened bosses in relatively thin sheet stock.

It is still another object of this invention to 'provide a bossformation of suitable dep'th to provide a satisfactory bolt receivingbore wherein the boss formed is of e depth considerably greater than thethickness of 4the stock from which 'theboss is extruded.

It is still another object 'of vthis vinvention lto provide a closed endsleeve-like boss formation that 'can be readily forned relatively 'thinfs'heet st ock'without 'perforating the stock yet one in which theclosed 'end .portion of the boss formation may he readily removed b'y aknockout operation that `will not injure 'the adjacent sleeve portionsofthe boss. t

It is 'also an object of this invention t'o provide an iniproved type ofdie 'for forming Closed end, 'sleevetype bosses.-

lIt is still another object of this invention to provide an improvedtype of boss forniin'g extrusion process.

yOther 'objects' and advantages of 'this Yinvention will become readily'apparent frori 'a readingof 'the following description and aconsideration of 'the 'related drawings wherein: i

Fig. l is a fragmentary 'sectional elevational view of a punch 'typeextrusion die used 'to for'r'n 'a boss embodying this invention, thisview showing `the beginning of the boss forming operation;

Fig. 2 is a v'ie'w similar 'to Fig'. l 'but showing the boss formingoperation at 'a second stage;

Fig. '3 is 'a view `similar to Figs. 1 and "2 but showing the boss'forming operation ata third stage;

Fig. 4 is `a view sirnila'r t'o Figs. l-3 but showing vthe completion of'the boss 'forming operation; Fig. 5 is 'a 'sec'tion'al elevational Viewof a modified form ofboss 'forming die having means associated withthe'pll'nches 'for C'Oh't'rolli'g 4the .extrusion height 0i' depth oftheboss;

Fig. v6 is an enlarged fragin'entafv sectional elevational vicvv of ahossjfoiination of l"the type formed `by "the `apparatus shown in 1-4';

Fig. 7 is a sectional elevational view of another Vrhodilied form ofextrusion die apparatus wherein only an 'upper punch V and die block areutilized;

ICC

Fig. 8 is a fragmehtaryelevational view of an engine compartment 'lire'vv'all having a plurality of compression extrusion formed closed endbos'ses 'formed therein;

fPig. '9 'is "a sectional elevational View taken along the' line 9 9 ofFig. 8; and

Fig. l0 is' a sectional elevational view of a portion of a fluidcoupling casing 'formed withcompression extrusion type, closed end,bosses i'n one of 'which a Vsealing plug has been mounted.

It has been Acommon practice 'to punch a hole in a plate 'and to thenthread the walls of the opening so as to provide a threaded recess toreceive 'a bolt. This 'practice has' been suitable for relatively'thickplates but it is highly unsatisfactory for relatively 'thin platesbecause of the inadequate 'thread area that is provided.

In anatteinpt to provide additional stock thickness around "the areaAwhere the plate is punched, attempts have been iliade -to extrude orstretch the material removed from the punched out a'r'ea into a collaror sleeve extending around vvthe hole periphery. This has providedadditional collar material around the punched out opening but thisstretched inater'ial 'forming the hole collar has been stressed to s ucha degree during the 'punch-out process that it us'ually fractures 'atcertain points around 'the collar-.periphery or, i'n the alternative,becomes so brittle that it cannot be properly machined during a threadforming operation.

The boss forming method herein disclosed redistributes the material`acted on in the punch 'out area so that a sturdy, thick, symmetrical,collar is formed around the p unc'h indented area. Furthermore, in theprocess of redistributin'g the stock material the material isWorkhardened so that 'it is strengthened and improved as regards'machinability and wearability. rThis method thus provides increasedcollar or boss 'depth 'for threading or bearing purposes Iand alsof'gives an improved Vcollar material that is stronger and more readilymachined. In addition, it be noted that 'this 'method initially providesa'close'd -exidLSleeve-type boss with a relatively thin knock-outplugrather than a completely pierced plate. This is quite important 'for'there are many applications 'Where an imperiorate plate is initiallydesired but one that may be readily pierced at one or more locations,subsequent toits 'fabncation, 'to pifovide an opening for receiving `abolt `or the like. Several s pecic applications of such 'platesaresubsequently 'described in referring `t'o 'Figs rSell) fof thefdrawings.By providing a plate that will 'completely seal oil a'n area yet 'onethat can be readily pierced by a simple knock-out operation, animportant improvement has been achieved particularly when the knock-'outVoperation leaves an opening surrounded by a sturdy,symmetrical'collarof a "depth considerably greater than the platethickness.

In `iigs. "114 of 'the drawings lll represents the upper extruding punchthat extends through an yopening v11 'in the stripper plate l2. l is thework piece or plate that is of a thickness 't. AThe plate P is adaptedto be supported 'on adie block i3 that has a 'stepped cylindrical bore`-or cavity le extending therethrough. Mounted -in the cavity 'lil "ofthe die 13 is 4'a lower extruding punch 16. lgower punch 16 may bereciprocably mounted in the die bore lil, 'as shown, for it can berigidly associated with 'the die block l3.` ln the Vdisclosed form thelower punch lo is free to move vertically downward a limited :amountbecause it is 'supported on a compression V'spring I3 that normallyurges it upwardly yoit" 'the die block seat `2l). When -a downwardlyldirected Aforce is applied to 'the upper end of 'the lower Ipunch z1'6then the 'base a of the lower punch V`16 compresses t'he spring 18 andthe lower 'pu'nch :1"6 seats on the Idie :block seat portion '20 asshown Ain :"Fi'gs. '2 and 2i.

The several 1steps 'or stages in 1the iformation of the iurthe lowerpunch head 1Gb is pressed into engagement with,

the underside of the plate P.

As a downwardly directed force is applied to the upper punch 10, seeFig. 2, the head b of the upper punch 10 is forced into and depressesthe portions of the plate P overlying the die cavity 14 and causes thelower punch 16 to move downwardly and seat on the die block seat portion20. During this initial downward movement of the upper punch 10, theportion 2S of the plate P, located in the pressure area between theupper and lower punch heads 10b, 16b respectively, are rst depressed adistance of approximately 1/3 the thickness t ofthe stock P and thenthese portions of plate P are compressed and squeezed radially outwardlyto begin the formation of the sleevelike boss portions 30 by compressiveextrusion.

As the downwardly directed force applied to the upper punch 10 isincreased, see Fig. 3, upper punch 10 continues to compress and squeezeout the portions 25 of the plate P located in the pressure area betweenthe punch heads 10b, 16b so that the plate portion 25 becomesprogressively thinner while the compressed plate material squeezed fromthe plate portion 2S is entrapped in the die cavity 14 and redistributedin the peripheral area around the sides of the punch head 10b to formthe sleevelike boss formation 30. It will be noted from Figs. 3 and 4that the increased punch applying forces, which cause compressiveextrusion of the sleeve-like boss portions 30, also develop reactionforces which cause the plate P to rise up off the top of the die block13. The space between the top of die block 13 and the plate P has beendenoted by the reference numeral r in Figs.

end boss 30 will now be de- In Fig. l the several cooperating parts ofthe 4 pression extrusion of the boss formations. In this manner theheight or depth of the extruded boss 60 may be controlled while stillproviding for substantially the same upper punch penetration x beneaththe top of the die block 13 before initiation of the compressiveextrusion. The concavity of the punch end faces also provides a knockoutplug 55 that has a thin outer periphery and a thick center andthis makesthe plug 55 easier to knock out.

Fig. 6 shows an enlarged view of a portion of a plate P having a closedend boss 30 formed therein according to the teachings of Figs. 1-4.Material of the boss 30 that has been work hardened during its processof formation has been labeled to indicate a hardness of 100 Rockwell Dwhereasthe plate P from which the boss 30 was formed initially had ahardness of only 55 Rockwell D. It will also be noticed that the radiusof curvature c at the base of the boss 30 is relatively Ilarge and thisprevents an undesirable stress concentration at .this portion of theboss and adds to its strength.

Fig. 7 is a view of another type of extrusion die apparatus similar tothat shown in Figs. 1-4. In this case, how-V ever, the lower punch 16 iscompletely omitted. This type of die is suitable for certain types ofboss formations but does not give the accuracy obtainable with the dieapparatus shown in Figs. l-4. The Figs. 1 4 apparatus seems moreproficient in maintaining the centered position of the upper punch 10with respect to the die block opening 14 so as to prevent cocking ortilting of the upper punch 10 with respect to the plate P and the diecavity 14a substantially the full depth of the cavity but leaves 3 and 4and it is apparent from Figs. 3 and 4 that this reaction space r becomesprogressively greater as the extrusion forces increase.

In applying this compressive extrusion process of boss formation toplates of several dilferent thicknesses, it has been found that anexcellent boss formation is achieved when (see Fig. 4) the depth ofpenetration x of the upper punch head 10b below the top of the die block13, before compressive extrusion of the metal begins, is substantiallyone-third (16) the thickness t of the plate stock P. It is to berealized that this particular relationship is not critical but one thatis merely recommended. Obviously this relationship will vary somewhatwith the variations in plate thickness, boss diameter and height andmaterial quality and hardness.

As previously pointed out one of the prime advantages of this inventionover the prior art is the work hardening of the boss material duringboss formation due to the compression extrusion of the boss material.This is a very definite improvement over the well known punch type ofboss forming process wherein the plate material is stretched to bossform and tensile stresses are set up in the boss material rather thancompressive stresses as with this process. It has been found that informing bosses according to this process from plate material of :iiginch -thickness and 55 Rockwell D hardness that this compressionextrusion process will provide a boss of about 5%;

inch height or depth and that the hardness of the boss formation willhave increased to about 100 Rockwell D (see Fig. 6).

In Fig. 5 is shown a modified form of boss forming extrusion dieapparatus that is quite similar to the form of apparatus shown in Figs.1-4 but differs therefrom in that the faces 50c and 46c of the upper andlower punches 50 and 46 respectively are each concavely dished. Thisdishing of the faces 46c, 50c of punch heads 46b, 50b provides anincreased area between the punch heads into' which the plate materialmay be squeezed during the coma thin'space between its end face 10c andthe bottom of the cavity 14a. This space provides for the thin knockoutplug 25a that seals oi the end of the sleeve-like boss 70. As with theforms of die apparatus shown in Figs. 1-5, this form of device alsowork-hardens the boss material due to the compression of the bossmaterial during formation thereof.

Figs. 8 and 9 show a portion of a vehicle engine compartment fire wallhaving a plurality of closed end sleevetype bosses 30 formed therein. Inthis case two of the bosses have had their knock-out plugs 25 removedand an accessory A has been bolted in these two open ended bosses bymeans of self tapping bolts 36. If at some later time additionalaccessories should be required, then the knock-out plugs 25 in some ofthe other bosses 30 could be removed. In the mean time the integralplugs 25 provide an air tight seal between opposite sides of the re wallD. It will also be noted that the bosses 30 formed by this compressionextrusion process do not have sharp edges so they are suitable for portsfor electrical wiring without the use of special wire supportingbushings to prevent cutting or wear of the wire insulating casings.

Fig. 10 shows the application of this compression method of bossextrusion to the casing of a fluid coupling. In this case one of theknock-out plugs 25 has been removed and a tapered screw plug 38 has beenthreaded into the open ended boss 30. While only a few examples of theutility of this type of boss formation have been shown, it is thought tobe obvious that vehicle door hinge plates and pulley hubs andinnumerable other parts of a motor vehicle could have this inventionapplied thereto. The applications of this invention to industries otherthan the motor vehicle industry are too numerous to even mention. Due tothis invention permitting the use of thinner sheet stock while givingincreased thickness of boss formations, considerable weight and costsavings can be achieved and for that reason this invention will be ofconsiderable importance in the aircraft industry.

I claim:

1. The method of forming a relatively thick walled, sleeve-type, closedend, boss in a relatively thin sheet of material comprising depressing acircular area therein to form a concavity in said sheet until theunderside of the depressed area lies below the general plane of theunderside of the sheet material a distance approximately one-third thethickness of said sheet, thereafter continuously and progressivelycompressing the center portion of the depressed area of said concavityby applying pressure to the opposed inner and outer bottom sides of saiddepressed center portion without bodily displacing said center portionto subject the intervening material to a squeeze action therebyextruding the material thereof in directions transversely of thecompressing force and entrapping said extruding material coupled withredistribution thereof in all directions parallel to the direction ofthe compressing force to form a thick walled, sleevetype, boss, closedby the remaining material of said squeezed central portion.

2. The method of forming a relatively thick walled, sleeve-type, closedend, boss in a relatively thin sheet of metal comprising depressing anannular area therein to form a concavity in said sheet until theunderside of the depressed area lies below the general plane of theunderside of the metal sheet a distance approximately one-third thethickness of said sheet, thereafter continuously and progressivelycompressing portions of the bottom of said depressed area of saidconcavity by applying pressure to the opposed concave and convex sidesof said depressed bottom portion without bodily displacing saiddepressed bottom portion to subject the intervening metal to a squeezeaction thereby extruding the metal thereof n directions transversely ofthe compressing force and entrapping said extruding metal at the outerperiphery of said depressed bottom portion coupled with redistributionof the entrapped extruding metal in all directions parallel to thedirection of the compressing force to form a thick walled, sleeve-type,boss, closed by the remaining metal of said squeezed portion.

References Cited in the file of this patent UNITED STATES PATENTS 64,197Clark Apr. 30, 1867 1,082,200 Knaebel Dec. 23, 1913 1,270,059 SchaeferJune 18, 1918 1,314,036 Amberg Aug. 26, 1919 1,408,917 Wilcox Mar. 7,1922 2,016,296 Rossborough Oct. 8, 1935 2,051,639 Kalmbacker Aug. 18,1936 2,213,812 Harper Sept. 3, 1940 2,451,511 Rice Oct. 19, 19482,627,652 Schweller Feb. 10, 1953 2,697,953 Chapman Dec. 28, 1954FOREIGN PATENTS 12,137 Great Britain Oct. 12, 1885 21,053 Great BritainNov. 21, 1900 725,881 Germany Oct. 1, 1942 France Nov. 8, 1950

